1) If you attack a planet that only has one ship in orbit (or has an Orbital Fleet Manager and only enough ships for one fleet) you will see the shield (garrison) icon disappear from the planet in the background before the battle sequence is completed in the combat viewer if the attacker is going to win
2) If you attempt to invade a planet, you can see the influence lines change in the background before the invasion combat sequence is completed in the combat viewer if the invader is going to win

Both of these are a minor spoiler. The timing should be adjusted so the combat is completed in each case before the main map is updated.